This is a shield that sits under the lip on the front and sides of the AMS - it's intended to be used when implementing a lighting mod where you place LED light strips on the bottom of the AMS to improve illumination within the printer interior. Placing the LEDs on the bottom of the AMS is a simple way to improve lighting that doesnt involve any changes to the printer.  These shields can be stuck to the bottom of the printer with a little thin double sided tape - they will stop the light shining out from under the printer.